岩体各向异性对江底隧道开挖变形与渗流影响分析

Analysis on the influence of rocks anisotropy on excavation deformation and seepage of underwater tunnel

摘要

以芜湖城南过江隧道江底段为研究背景，采用水-力耦合数值模拟方法对隧道开挖与江水渗流作用下各向异性围岩的变形与渗流响应进行研究，分析不同优势微裂隙倾角、江水位以及支护水压等因素的影响。研究表明：江底隧道开挖引起的围岩变形主要由江水渗流作用决定，支护水压失效将造成围岩产生影响安全施工的过大变形，且江水位变大越显著。开挖隧道围岩变形受岩体各向异性结构与支护水压的影响，围岩拱顶方向沉降随优势微裂隙倾角的增大呈先增后减的变化规律，微裂隙倾角越小洞周水压力明显降低区域越大，江水渗流将造成地表更大范围产生较大沉降；随着支护水压的增大，围岩变形逐渐减小，但施加的支护水压过大会引起江底地表大幅隆起，适宜支护水压的选取非常关键但受岩体各向异性结构特征的影响。

Abstract

Taking the Yangtze River crossing section in Wuhu Chengnan tunnel as research background, the coupled hydro-mechanical numerical model was utilized to study the deformation and seepage responses of anisotropic surrounding rocks under the action of tunnel excavation and river seepage. The influences of dominant-developed microcracks inclination, river level, and supporting water pressure on tunnel excavation responses were analyzed. The research result showed that the deformation induced by underwater tunnel excavation was mainly determined by river seepage action. Withdrawal of supporting water pressure would lead to excessive deformation of the surrounding rocks with safety risks, which was more obvious with the increase of river level. The tunnel excavation-induced deformation was also affected by the anisotropic structure of surrounding rocks and supporting water pressure. With the increase of dominant-developed microcracks inclination, the settlement of surrounding rocks in arch roof direction first increased and then decreased. The smaller the microcracks inclination, the greater the water pressure obviously decreased region around the excavated tunnel, as a result larger underwater-ground subsidence scope would be triggered by river seepage action. With the increase of supporting water pressure, the excavated-induced deformation around the tunnel gradually decreased, but excessive supporting water pressure would cause significant ground uplift displacement. It's of importance to select suitable supporting water pressure, but it was influenced by the anisotropic structural characteristic of surrounding rocks.

关键词

江底隧道 / 岩体各向异性 / 水-力耦合 / 数值计算

Key words

underwater tunnel / rocks anisotropy / hydro-mechanical coupling / numerical computation

Author summay

张红彬(1983—), 男, 高级工程师, 硕士, 主要从事轨道交通和过江隧道工程质量安全评价研究。Email: [e-mail]

基金资助

安徽省自然科学基金项目(2208085ME153)

安徽高校协同创新项目(GXXT-2022-020)